Perfectionnement aux appareils de production de pellicules à partir de matières résineuses thermoplastiques filmogènes

摘要

1,153,604. Producing tubular films. J. THORDARSON. 27 Oct., 1966 [27 Oct., 1965], No. 48251/66. Heading B5B. As shown in Fig. 1 an apparatus for producing tubular film 2 comprises an extrusion head 1 provided with an annular extrusion orifice through which synthetic organic thermoplastic material is melt extruded in the form of a tube 2a. Surrounding the extrusion orifice is an air blower in the form of a box 3 having an annular slot 3a through which a stream of cooling air is directed upwards around the extruded inflated tubular film. The tubular film is drawn upwards in the usual manner by means of a pair of nip rolls 4a, 4a which also prevent the air or other gas with which the tubular film is inflated from escaping. The film is inflated by introducing air into the interior of the film at constant pressure through the pipe 15 and the hollow members 11 and 12 supporting a cooling column 6 positioned inside the film and through the cooling column itself. The air flows out of the bottom of the cooling column 6 and upwards between the cooling column 6 and the tubular film (as shown by the arrows 5) until the film is inflated to the required degree, after which only sufficient air is introduced into the tubular film to replace the very small amount of air leaving out of the flattened film between the pinch rolls 4a. A fan 7 driven by an electric motor 18 near the top of the interior of the column 6 (Fig. 2) draws hot air from the upper portion of the interior of the inflated tubular film through the inlets 19 and then impels it downwards inside the column 6 over an axial internally cooled tubular cooling element 17 as shown by the arrows 51. Stationary baffles 9 inside the lower portion of the cooling element 6 impart a rotary motion to the cooled air travelling downwards through the lower portion of the column and thereby cause the air the rotate a nozzle 8 rotatably mounted on the lower end of the column. The nozzle 8 is provided with one or more radial outlet ducts which direct cooled air on to the inner surface of the tube 2a so that the latter is internally as well as externally cooled. The air is then drawn upwards between the column 6 and the inflated tubular film 2 and again enters the inlet ports near the top of the column 6. The shaft 11 which extends through the core 12 of the extrusion head accommodates inlet and outlet ducts 13 and 14 for the circulation of cooling water through the cooling element 17 and electric power leads 16 for operating the fan 7.